The invention generally relates structures for supporting one or more diagnostic or therapeutic elements in contact with body tissue. In a more particular sense, the invention relates to structures well suited for supporting one or more electrode elements within the heart.
The treatment of cardiac arrhythmias requires electrodes capable of creating tissue lesions having a diversity of different geometries and characteristics, depending upon the particular physiology of the arrhythmia to be treated.
For example, it is believed the treatment of atrial fibrillation and flutter requires the formation of continuous lesions of different lengths and curvilinear shapes in heart tissue. These lesion patterns require the deployment within the heart of flexible ablating elements having multiple ablating regions. The formation of these lesions by ablation can provide the same therapeutic benefits that the complex incision patterns that the surgical maze procedure presently provides, but without invasive, open heart surgery.
By way of another example, small and shallow lesions are desired in the sinus node for sinus node modifications, or along the A-V groove for various accessory pathway ablations, or along the slow zone of the tricuspid isthmus for atrial flutter (AFL) or AV node slow pathways ablations. However, the elimination of ventricular tachycardia (VT) substrates is thought to require significantly larger and deeper lesions.
There also remains the need to create lesions having relatively large surface areas with shallow depths.
The task is made more difficult because heart chambers vary in size from individual to individual. They also vary according to the condition of the patient. One common effect of heart disease is the enlargement of the heart chambers. For example, in a heart experiencing atrial fibrillation, the size of the atrium can be up to three times that of a normal atrium.
A need exists for electrode support structures that can create lesions of different geometries and characteristics, and which can readily adopt to different contours and geometries within a body region, e.g., the heart.
The invention provides structures for supporting operative therapeutic or diagnostic elements within an interior body region, like the heart. The structures possess the requisite flexibility and maneuverability permitting safe and easy introduction into the body region. Once deployed in the body region, the structures possess the capability to conform to different tissue contours and geometries to provide intimate contact between the operative elements and tissue.
In one embodiment, the invention provides a catheter assembly comprising a first branch body having a first axis and a second branch body, which extends in a non-parallel relationship with respect to the first axis. The assembly also includes a control to rotate the second branch body about the first axis.
In one embodiment, the second branch body includes a second axis. In this embodiment, a control rotates the second branch body about the second axis, as well as move the second branch body axially along the second axis.
In one embodiment, the second branch body carries at least one operative element, e.g., an electrode.
Another embodiment of the invention provides a method for forming lesions in the left atrium. The method provides a catheter assembly comprising a first branch body having a first axis, a second branch body extending in a non-parallel relationship with respect to the first axis, and at least one electrode carried by the second branch body. The method locates the first branch body within a pulmonary vein within the left atrium. The method locates the electrode carried by the second branch body in contact with endocardial tissue outside the pulmonary vein, while the first branch body is located within the pulmonary vein. The method transmits ablation energy from the electrode to contacted endocardial tissue while the first branch body is located within the pulmonary vein.